1. Field:
This invention relates to electrolytic techniques and apparatus for recovering silver from silver-laden fixer solutions derived from photographic and X-ray film processors.
2. Prior Art:
Various apparatus and techniques are utilized for the recovery of silver from silver-laden fixer solutions from photographic film processors.
Electrolytic techniques and apparatus employed in silver recovery systems are disclosed in the following Burgess U.S. Pat. Nos. 3,926,768 and 3,959,110; Bentley U.S. Pat. No. 3,715,291; Scheidegger U.S. Pat. No. 4,139,431; Staples U.S. Pat. No. 4,166,781; Biles U.S. Pat. Nos. 4,362,608 and 4,287,044; Wayden U.S. Pat. No. 3,964,990; Idota et al U. S. Pat. No. 4,111,766; and Higgins U.S. Pat. Nos. 4,127,465 and 4,078,983.
The Higgins patents are representative of electrolytic silver recovery systems associated with photographic film processors wherein current is adjusted proportionately in relation to the rate of film processed. Extensive electronic sensing and control circuitry is required in systems employing techniques such as those employed by Higgins.
Other systems, such as those disclosed in the Burgess patents, employ a precollection chamber into which spent fixer solution is collected. Upon collection of a preset volume of solution, the spent (silver-laden) fixer solution is dispensed automatically into an electrolytic cell which is full of treated (de-silvered) fixed solution. The cell, however, has only one discharge port, which is an overflow port. Silver-laden solution flowing into the upper portions of the cell will tend to make the upper portions of the solution in the container silver-rich. The overflow of this silver-rich solution in the upper regions of the container will tend to occur in disproportionate amounts in comparison with the original resident low-silver solution in the container. Thus, silver will be lost to the drain without being treated because of the structure of the container and the manner of introducing silver-rich solution.